Article of Footwear with a Stretchable Upper and an Articulated Sole Structure

ABSTRACT

An article of footwear is disclosed that includes at least one of a stretchable upper and an articulated sole structure. The upper may include an exterior layer and an interior layer. The exterior layer forms at least a portion of an exterior of the upper, and the exterior layer includes a plurality of incisions that extend through the exterior layer. The interior layer is located adjacent an inner surface of the exterior layer, and the interior layer is exposed through the incisions. The sole structure may include a connecting portion and a plurality of discrete sole elements. The connecting portion is positioned adjacent the upper and may extend along a longitudinal length of the upper. The sole elements extend from the connecting portion, and the sole elements are separated by a plurality of sipes that extend upward into the sole structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 11/222,508, titled “Article of Footwear with aStretchable Upper and an Articulated Sole Structure” and filed Sep. 8,2005, which application is a continuation-in-part application of andclaims priority to U.S. patent application Ser. No. 10/681,321 (now U.S.Pat. No. 6,990,755), titled “Article of Footwear with a StretchableUpper and an Articulated Sole Structure” and filed Oct. 9, 2003.application Ser. Nos. 11/222,508 and 10/681,321, in their entirety, areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of footwear. The inventionconcerns, more particularly, an article of footwear having a stretchableupper and a sole structure with a plurality of incisions that impart anarticulated configuration with flexibility in selected directions.

2. Description of Background Art

Conventional articles of athletic footwear include two primary elements,an upper and a sole structure. The upper provides a covering for thefoot that securely receives and positions the foot with respect to thesole structure. In addition, the upper may have a configuration thatprotects the foot and provides ventilation, thereby cooling the foot andremoving perspiration. The sole structure is secured to a lower surfaceof the upper and is generally positioned between the foot and theground. In addition to attenuating ground reaction forces and absorbingenergy (i.e., imparting cushioning), the sole structure may providetraction and control potentially harmful foot motion, such as overpronation. Accordingly, the upper and the sole structure operatecooperatively to provide a comfortable structure that is suited for awide variety of ambulatory activities, such as walking and running Thegeneral features and configuration of the upper and the sole structureare discussed in greater detail below.

The upper forms a void on the interior of the footwear for receiving thefoot. The void has the general shape of the foot, and access to the voidis provided by an ankle opening. Accordingly, the upper extends over theinstep and toe areas of the foot, along the medial and lateral sides ofthe foot, and around the heel area of the foot. A lacing system is oftenincorporated into the upper to selectively increase the size of theankle opening and permit the wearer to modify certain dimensions of theupper, particularly girth, to accommodate feet with varying proportions.In addition, the upper may include a tongue that extends under thelacing system to enhance the comfort of the footwear, and the upper mayinclude a heel counter to limit movement of the heel.

Various materials may be utilized in manufacturing the upper. The upperof an article of athletic footwear, for example, may be formed frommultiple material layers that include an exterior layer, a middle layer,and an interior layer. The materials forming the exterior layer of theupper may be selected based upon the properties of wear-resistance,flexibility, and air-permeability, for example. With regard to theexterior layer, the toe area and the heel area may be formed of leather,synthetic leather, or a rubber material to impart a relatively highdegree of wear-resistance. Leather, synthetic leather, and rubbermaterials may not exhibit the desired degree of flexibility andair-permeability. Accordingly, various other areas of the exterior layerof the upper may be formed from a synthetic textile. The exterior layerof the upper may be formed, therefore, from numerous material elementsthat each impart different properties to specific areas of the upper.

A middle layer of the upper may be formed from a lightweight polymerfoam material that provides cushioning and protects the foot fromobjects that may contact the upper. Similarly, an interior layer of theupper may be formed of a moisture-wicking textile that removesperspiration from the area immediately surrounding the foot. In somearticles of athletic footwear, the various layers may be joined with anadhesive, and stitching may be utilized to join elements within a singlelayer or to reinforce specific areas of the upper.

The sole structure generally incorporates multiple layers that areconventionally referred to as an insole, a midsole, and an outsole. Theinsole is a thin, cushioning member located within the upper andadjacent the plantar (lower) surface of the foot to enhance footwearcomfort. The midsole, which is traditionally attached to the upper alongthe entire length of the upper, forms the middle layer of the solestructure and serves a variety of purposes that include controlling footmotions and providing cushioning. The outsole forms theground-contacting element of footwear and is usually fashioned from adurable, wear-resistant material that includes texturing to improvetraction.

The primary element of a conventional midsole is a resilient, polymerfoam material, such as polyurethane or ethylvinylacetate, that extendsthroughout the length of the footwear. The properties of the polymerfoam material in the midsole are primarily dependent upon factors thatinclude the dimensional configuration of the midsole and the specificcharacteristics of the material selected for the polymer foam, includingthe density of the polymer foam material. By varying these factorsthroughout the midsole, the relative stiffness, degree of groundreaction force attenuation, and energy absorption properties may bealtered to meet the specific demands of the activity for which thefootwear is intended to be used.

In addition to polymer foam materials, conventional midsoles mayinclude, for example, stability devices that resist over-pronation andmoderators that distribute ground reaction forces. The use of polymerfoam materials in athletic footwear midsoles, while providing protectionagainst ground reaction forces, may introduce instability thatcontributes to a tendency for over-pronation. Although pronation isnormal, it may be a potential source of foot and leg injury,particularly if it is excessive. Stability devices are oftenincorporated into the polymer foam material of the midsoles to controlthe degree of pronation in the foot. Examples of stability devices arefound in U.S. Pat. Nos. 4,255,877 to Bowerman; 4,287,675 to Norton etal.; 4,288,929 to Norton et al.; 4,354,318 to Frederick et al.;4,364,188 to Turner et al.; 4,364,189 to Bates; and 5,247,742 to Kilgoreet al. In addition to stability devices, conventional midsoles mayinclude fluid-filled bladders, as disclosed in U.S. Pat. Nos. 4,183,156and 4,219,945 to Rudy, for example.

SUMMARY OF THE INVENTION

The present invention is an article of footwear having at least one of astretchable upper and an articulated sole structure. In one aspect ofthe invention, the upper includes an exterior layer and an interiorlayer. The exterior layer forms at least a portion of an exterior of theupper, and the exterior layer includes a plurality of incisions thatextend through the exterior layer. The interior layer is locatedadjacent at least a portion of an inner surface of the exterior layer,and the interior layer is exposed through at least a portion of theincisions.

The incisions may include a first group and a second group. The firstgroup may be oriented to provide stretch in a direction that extendsbetween a medial side and a lateral side of the upper, and the secondgroup of the incisions may be positioned adjacent the medial side and ina forefoot region of the upper.

In another aspect of the invention, the sole structure includes aconnecting portion and a plurality of discrete sole elements. Theconnecting portion is positioned adjacent the upper and may extend alonga longitudinal length of the upper. The sole elements extend downwardfrom the connecting portion, and the sole elements are separated by aplurality of sipes that extend upward into the midsole.

The connecting portion may be configured to have a varying thickness.Accordingly, the connecting portion may exhibit a first thickness in theforefoot region of the footwear, a second thickness in a midfoot regionof the footwear, and a third thickness in the heel region of thefootwear, with the first and third thicknesses being less than thesecond thickness. In addition, the sipes may include a first sipe, asecond sipe, and a plurality of third sipes. The first sipe may beoriented in the longitudinal direction and may extend through an entirelength of the midsole. The second sipe may extend in the longitudinaldirection and through only a portion of the length of the midsole. Thethird sipes may extend laterally from the medial side to the lateralside of the midsole.

The advantages and features of novelty characterizing the presentinvention are pointed out with particularity in the appended claims. Togain an improved understanding of the advantages and features ofnovelty, however, reference may be made to the following descriptivematter and accompanying drawings that describe and illustrate variousembodiments and concepts related to the invention.

DESCRIPTION OF THE DRAWINGS

The foregoing Summary of the Invention, as well as the followingDetailed Description of the Invention, will be better understood whenread in conjunction with the accompanying drawings.

FIG. 1 is a lateral elevational view of the footwear.

FIG. 2 is a medial elevational view of the footwear.

FIG. 3 is a top plan view of the footwear.

FIG. 4A is a first cross-sectional view of the footwear, as defined bysection line 4A-4A in FIG. 3.

FIG. 4B is a second cross-sectional view of the footwear, as defined bysection line 4B-4B in FIG. 3.

FIG. 5 is a rear elevational view of the footwear.

FIG. 6 is a lateral elevational view that illustrates the footwear whenreceiving a foot.

FIG. 7 is a partial lateral elevational view of the footwear in a flexedconfiguration.

FIG. 8 is a bottom plan view of the sole structure.

FIG. 9A is a first cross-sectional view of the sole structure, asdefined by section line 9A-9A in FIG. 8.

FIG. 9B is a second cross-sectional view of the sole structure, asdefined by section line 9B-9B in FIG. 8.

FIG. 9C is a third cross-sectional view of the sole structure, asdefined by section line 9C-9C in FIG. 8.

FIG. 9D is a fourth cross-sectional view of the sole structure, asdefined by section line 9D-9D in FIG. 8.

FIG. 9E is a fifth cross-sectional view of the sole structure, asdefined by section line 9E-9E in FIG. 8.

FIG. 9F is a sixth cross-sectional view of the sole structure, asdefined by section line 9F-9F in FIG. 8.

FIG. 9G is a seventh cross-sectional view of the sole structure, asdefined by section line 9G-9G in FIG. 8.

FIG. 10A is a cross-sectional view of an alternate embodiment thatcorresponds with the location of section line 9A-9A in FIG. 8.

FIG. 11 is a bottom plan view of an insole portion of the footwear.

FIG. 12 is a bottom plan view of another insole portion of the footwear.

FIG. 13A is an exploded perspective view of a mold for manufacturing amidsole of the sole structure.

FIG. 13B is a cross-sectional view of the mold, as defined by sectionline 13B-13B in FIG. 13A.

FIG. 13C is a cross-sectional view corresponding to FIG. 13B and havinga polymer material in the mold.

FIG. 13D is an exploded perspective view of the mold and the midsole.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion and accompanying figures disclose an article offootwear 10 in accordance with the present invention. Footwear 10 isdepicted in the figures and discussed below as having a configurationthat is suitable for athletic activities, particularly running. Theconcepts disclosed with respect to footwear 10 may, however, be appliedto footwear styles that are specifically designed for a wide range ofother athletic activities, including basketball, baseball, football,soccer, walking, and hiking, for example, and may also be applied tovarious non-athletic footwear styles. Accordingly, one skilled in therelevant art will recognize that the concepts disclosed herein may beapplied to a wide range of footwear styles and are not limited to thespecific embodiments discussed below and depicted in the figures.

Footwear 10 is depicted in FIGS. 1-7 and includes an upper 20 and a solestructure 30. Upper 20 is formed from various material elements that arestitched or adhesively-bonded together to form an interior void thatcomfortably receives a foot and secures the position of the footrelative to sole structure 30. Sole structure 30 is secured to a lowerportion of upper 20 and provides a durable, wear-resistant component forattenuating ground reaction forces and absorbing energy (i.e., providingcushioning) as footwear 10 impacts the ground.

Many conventional articles of footwear exhibit a configuration thatcontrols the motion of the foot during running or other activities. Aconventional sole structure, for example, may have a relatively stiff orinflexible construction that inhibits the natural motion of the foot.Upper 20 and sole structure 30 have a structure that cooperativelyarticulate, flex, stretch, or otherwise move to provide an individualwith a sensation of natural, barefoot running That is, upper 20 and solestructure 30 are configured to complement the natural motion of the footduring running or other activities. In contrast with barefoot running,however, sole structure 30 attenuates ground reaction forces and absorbsenergy to cushion the foot and decrease the overall stress upon thefoot.

For purposes of reference, footwear 10 may be divided into three generalregions: a forefoot region 11, a midfoot region 12, and a heel region13, as defined in FIGS. 1 and 2. Regions 11-13 are not intended todemarcate precise areas of footwear 10. Rather, regions 11-13 areintended to represent general areas of footwear 10 that provide a frameof reference during the following discussion. Although regions 11-13apply generally to footwear 10, references to regions 11-13 may alsoapply specifically to upper 20, sole structure 30, or an individualcomponent or portion within either of upper 20 or sole structure 30.

The various material elements forming upper 20, which will be describedin greater detail below, combine to provide a structure having a lateralside 21, an opposite medial side 22, a tongue 23, and a lasting sock 24that form the void within upper 20. Lateral side 21 extends through eachof regions 11-13 and is generally configured to contact and cover alateral surface of the foot. A portion of lateral side 21 extends overan instep of the foot and overlaps a lateral side of tongue 23. Medialside 22 has a similar configuration that generally corresponds with amedial surface of the foot. A portion of medial side 22 also extendsover the instep of the foot and overlaps an opposite medial side oftongue 23. In addition, lateral side 21, medial side 22, and tongue 23cooperatively form an ankle opening 25 in heel region 13 to provide thefoot with access to the void within upper 20.

Tongue 23 extends longitudinally along upper 20 and is positioned tocontact the instep area of the foot. Side portions of tongue 23 aresecured to an interior surface of each of lateral side 21 and medialside 22. A lace 26 extends over tongue 23 and through apertures formedin lateral side 21 and medial side 22. Tongue 23 extends under lace 26to separate lace 26 from the instep area of the foot. By increasing thetension in lace 26, the tension in lateral side 21 and medial side 22may be increased so as to draw lateral side 21 and medial side 22 intocontact with the foot. Similarly, by decreasing the tension in lace 26,the tension in lateral side 21 and medial side 22 may be decreased so asto provide additional volume for the foot within upper 20. This generalconfiguration provides, therefore, a mechanism for adjusting the fit ofupper 20 and accommodating various foot dimensions.

A variety of materials are suitable for upper 20, including thematerials that are conventionally utilized in footwear uppers.Accordingly, upper 20 may be formed from combinations of leather,synthetic leather, natural or synthetic textiles, polymer sheets,polymer foams, mesh textiles, felts, non-woven polymers, or rubbermaterials, for example. The exposed portions of upper 20 are formed fromtwo coextensive layers of material that are stitched or adhesivelybonded together. As depicted in FIG. 4A and 4B, the layers include anexterior layer 14 and an adjacent interior layer 15. Exterior layer 14is positioned on an exterior of upper 20, and interior layer 15 ispositioned on an interior of upper 20 so as to form a surface of thevoid within upper 20. Lasting sock 24 is secured to a lower edge oflayers 14 and 15 and extends along the upper surface of sole structure30.

The materials forming layers 14 and 15 may vary in different areas ofupper 20, and only one or more of layers 14 and 15 may be present insome areas of upper 20. With respect to the areas of lateral side 21 andmedial side 22 that extend through forefoot region 11 and midfoot region12, for example, suitable materials for exterior layer 14 are varioustextiles, whether woven or non-woven, leather, synthetic leather, or asingle layer mesh, for example, and interior layer 15 may be formed fromsimilar materials. The materials that form tongue 23 and the area aroundankle opening 25 may be different than the materials discussed above.For example, exterior layer 14 may be formed from a material thatincludes two spaced textile layers interconnected by a plurality ofconnecting fibers. One or both of the textile layers may be a meshmaterial to enhance the air-permeability of upper 20 in this area. Inaddition, a foam material may be interposed between exterior layer 14and interior layer 15.

Whereas the areas discussed above are formed from both layers 14 and 15,a portion of upper 20 may only include a single layer. Referring toFIGS. 4B and 5, the area of upper 20 located within heel region 13 andextending around the rear portion of heel region 13 is formed solelyfrom interior layer 15. That is, exterior layer 14 and is absent in thisportion of heel region 13 such that interior layer 15 forms both theexterior and interior of upper 20. In some embodiments of the invention,however, the portion of upper 20 in heel region 13 may incorporate aconventional heel counter formed of a semi-rigid polymer material, forexample, to ensure that the heel remains properly positioned withrespect to upper 20. The heel counter may be located on an exterior ofupper 20 or within the various material elements forming upper 20. Aswill be discussed below, however, the configuration of upper 20 and solestructure 30 does not necessitate the presence of a heel counter.

Based upon the above discussion, the various portions of upper 20include different combinations of materials that form layers 14 and 15.For example, the materials forming exterior layer 14 and interior layer15 in the areas of tongue 23 and around ankle opening 25 may bedifferent than the materials forming exterior layer 14 and interiorlayer 15 in the areas of lateral side 21 and medial side 22 that extendthrough forefoot region 11 and midfoot region 12. As depicted in theFigures, however, the material forming interior layer 15 is the samethroughout both of these areas, and the same material extends around therearmost portion of heel region 13. Accordingly, the same material mayform a substantial portion of the interior surface of upper 20. Infurther embodiments, however, different materials may be utilized forthe various areas of interior layer 15, or upper 20 may include morethan two layers of material.

Exterior layer 14 includes a plurality of incisions 27 a and 27 b thatexpose underlying portions of interior layer 15. By exposing interiorlayer 15, the stretch properties of upper 20 are selectively modified.In areas where no incisions 27 a and 27 b are present, each of layers 14and 15 contribute to the stretch-resistance of upper 20. In areas whereincisions 27 a and 27 b are present, however, incisions 27 a and 27 bpermit exterior layer 14 to stretch to a greater degree. Accordingly,incisions 27 a and 27 b are formed in upper 20 to selectively vary thedegree of stretch in specific portions of upper 20. In addition,incisions 27 a and 27 b may be utilized to vary the air-permeability,flexibility, and overall aesthetics (e.g., color) of upper 20.

With reference to FIGS. 1-3, incisions 27 a and 27 b are depicted asbeing distributed over the areas of lateral side 21 and medial side 22that extend through forefoot region 11 and midfoot region 12. Ingeneral, incisions 27 a have a linear configuration and are oriented toextend longitudinally with respect to footwear 10. That is, incisions 27a are oriented in a direction that extends between forefoot region 11and heel region 13. In an area of forefoot region 11 that correspondswith the hallux (i.e., the big toe), however, incisions 27 b areoriented to extend laterally.

The orientation of incisions 27 a and 27 b has an effect upon thedirections of stretch imparted by incisions 27 a and 27 b. In general,incisions 27 a and 27 b do not increase the stretch in a direction thatcorresponds with the linear orientation of incisions 27 a and 27 b. Thatis, a particular incision 27 a and 27 b does not increase the stretch ina direction that is parallel to that incision 27. Incisions 27 a and 27b do, however, increase the stretch of upper 20 in a direction that isperpendicular to the linear orientation of incisions 27 a and 27 b.

Incisions 27 a are depicted as forming lines of slits that extendlongitudinally, and the incisions 27 a in adjacent lines are offset fromeach other. Similarly, incisions 27 b are depicted as forming lines ofslits that extend laterally, and the incisions 27 b in adjacent linesare offset from each other. The various incisions 27 a and 27 b,however, may be added to upper 20 in other arrangements. For example,incisions 27 a and 27 b may be offset so as to not form lines, orincisions 27 a and 27 b may be randomly placed with respect to upper 20.

Incisions 27 a, as discussed above, are oriented longitudinally withrespect to footwear 10. When a foot is placed within upper 20, asdepicted in FIG. 6, and exerts a stretching force upon upper 20, andparticularly upon exterior layer 14, incisions 27 a permit upper 20 tostretch in a manner that increases the girth of upper 20. That is,incisions 27 a stretch in a direction that is perpendicular to thelongitudinal orientation of incisions 27 a. Incisions 27 b stretch in asimilar manner. As discussed above, however, incisions 27 b are orientedlaterally. Accordingly, incisions 27 b stretch in the longitudinaldirection.

Incisions 27 a and 27 b are depicted as being linear cuts in exteriorlayer 14. When a stretching force is exerted upon exterior layer 14 andin a direction that is generally perpendicular to one or more ofincisions 27 a and 27 b, edges of the incisions 27 a and 27 b separateand form a generally elliptical shape with pointed ends, as depicted inFIG. 6. Incisions 27 a and 27 b are depicted as having a relativelylinear and short configuration. Within the scope of the presentinvention, however, incisions 27 a and 27 b may exhibit a straight orcurved configuration, for example, and the length of the variousincisions 27 a and 27 b may be modified. Differences in the shape andlength of incisions 27 a and 27 b may be utilized, for example, tomodify the desired degree of stretch in upper 20, the air permeabilityof upper 20, and the flexibility and overall aesthetics of upper 20.Factors that may also be considered when determining the shape andlength of incisions 27 a and 27 b include the materials utilized withinupper 20, the degree of inherent stretch in the materials, and thedirections in which stretch is desired, for example.

The materials forming a conventional upper are often stitched orotherwise sewn to each other, and an adhesive bond may be utilized tosecure coextensive portions of the materials to each other. As with aconventional upper, layers 14 and 15 are arranged in a coextensivemanner and may be bonded to each other. In some embodiments, however,layers 14 and 15 may be separate with no bonding. That is, layers 14 and15 may be positioned adjacent to each other but not secured togetherexcept at edges or stress points, for example, so that interior layer 15is unsecured to the exterior layer 14 in areas that are proximal toincisions 27 a and 27 b. An advantage of this configuration is thatexterior layer 14 may stretch and move independent of interior layer 15.That is, incisions 27 a and 27 b may permit stretch in exterior layer 14that is not significantly hindered through an adhesion between layers 14and 15. In general, therefore, layers 14 and 15 may not be adhered orotherwise secured together in areas that include incisions 27 a and 27b.

Incisions 27 a and 27 b are depicted as being formed in exterior layer14. Within the scope of the present invention, however, incisions 27 aand 27 b may also be formed in one or both of layers 14 and 15. Forexample, incisions 27 a and 27 b may be formed in only exterior layer14, both exterior layer 14 and interior layer 15, or in only interiorlayer 15. In some embodiments where both of layers 14 and 15 includeincisions 27 a and 27 b, the incisions 27 a and 27 b may aligned oroffset. Based upon the preceding discussion, therefore, theconfiguration of incisions 27 a and 27 b may vary considerably withinthe scope of the present invention.

Incisions 27 a and 27 b may be formed through a variety of methods. Asan example, incisions 27 a and 27 b may be formed with a cuttinginstrument, such as a die, knife, or razor. In addition to cuttinginstruments, a laser apparatus may be employed to form incisions 27 aand 27 b and cut exterior layer 14 from a larger material element.Incisions 27 a and 27 b may be formed, therefore, by directing a laserat exterior layer 14 to remove the portions of exterior layer 14 thatcorrespond with incisions 27 a and 27 b. The width of incisions 27 a and27 b may approximately correspond with the width of the laser.Alternately, multiple passes of the laser may be utilized to formincisions 27 a and 27 b with a greater width. The laser apparatus mayhave the capacity to produce a laser beam of variable intensity byadjusting the power of the laser beam. In addition to adjusting thepower, the focus of the laser beam and the velocity of the laser beamrelative to exterior layer 14 may be varied. An example of a suitablelaser apparatus is any of the conventional CO₂ or Nd:YAG laserapparatuses, as disclosed in U.S. Pat. Nos. 5,990,444 and 6,140,602 toCostin, which are hereby incorporated by reference.

For materials such as synthetic leather, leather, polymer sheets, andpolymer textiles, which are often incorporated into footwear uppers, thepower of the laser beam that forms incisions 27 a and 27 b is generallyin a range of 0.25 to 25 watts, for example. If the laser beam has arelatively narrow focus, the power of the laser beam may be decreased toaccount for the greater energy per unit area in the laser beam.Similarly, if the laser beam has a relatively wide focus, the power ofthe laser beam may be increased to account for the lesser energy perunit area in the laser beam. Modifications to the velocity of the laserbeam may also be utilized to account for the focus and power of thelaser beam. Whereas materials such as leather, synthetic leather, andpolymer textiles may require a relatively small power to form incisions27 a and 27 b, other materials such as high-density polymers may requiregreater power to form incisions 27 a and 27 b to the same depth.Accordingly, many factors are considered in determining the properpower, focus, and/or velocity of the laser beam for forming incisions 27a and 27 b.

The laser apparatus may include an emitter for the laser beam that movesadjacent to exterior layer 14 and forms incisions 27 a and 27 b inexterior layer 14. That is, the shape of the various incisions 27 a and27 b may be controlled by movements of the laser apparatus relative toexterior layer 14. Alternately, the laser beam may reflect off of one ormore movable or pivotable mirrors, and the shape of incisions 27 a and27 b in exterior layer 14 may be controlled by movements of the mirrors.

The laser beam heats selected areas of exterior layer 14 and formsincisions 27 a and 27 b by burning or incinerating the selected areas ofexterior layer 14. In order to prevent other areas of exterior layer 14from unintentionally burning, incisions 27 a and 27 b may be formed inthe presence of a non-combustible fluid, such as carbon dioxide ornitrogen. That is, the laser apparatus may be configured to emit anon-combustible fluid when the laser beam is forming incisions 27 a and27 b.

Once incisions 27 a and 27 b are formed in exterior layer 14, thevarious elements of upper 20 are assembled around a last that impartsthe general shape of a foot to the void within upper 20. That is, thevarious elements are assembled around the last to form lateral side 21and medial side 22 of upper 20, which extend from forefoot region 11 toheel region 13. In addition, the instep area is formed to include tongue23 and lace 26, for example, and ankle opening 25 is formed in heelregion 13. Lasting sock 24 is also secured to lower edges of lateralside 21 and medial side 22, and lasting sock 24 extends under the lastto form a lower surface of the void within upper 20. A portion of solestructure 30 is then permanently secured to a lower area of upper 20,which includes lasting sock 24. In joining upper 20 and sole structure30, adhesives, stitching, or a combination of adhesives and stitchingmay be utilized. In this manner, upper 20 is secured to sole structure30 through a substantially conventional process.

Sole structure 30 includes an insole 31 (depicted in greater detailbelow), a midsole 32, and an outsole 33. Insole 31 is positioned withinupper 20 and adjacent to the upper surface of lasting sock 24 in orderto contact the plantar (lower) surface of the foot and enhance thecomfort of footwear 10. Midsole 32 is secured to a lower portion ofupper 20, including lasting sock 24, and is positioned to extend underthe foot during use. Among other purposes, midsole 32 attenuates groundreaction forces when walking or running, for example Suitable materialsfor midsole 32 are any of the conventional polymer foams that areutilized in footwear midsoles, including ethylvinylacetate andpolyurethane foam. Midsole 32 may also be formed from a relativelylightweight polyurethane foam having a specific gravity of approximately0.22, as manufactured by Bayer AG under the BAYFLEX trademark. Outsole33 is secured to a lower surface of midsole 32 to providewear-resistance, and outsole 33 may be recessed within midsole 32.Although outsole 33 may extend throughout the lower surface of midsole32, outsole 33 is located within heel portion 13 in the particularembodiment depicted in the figures. Suitable materials for outsole 33include any of the conventional rubber materials that are utilized infootwear outsoles, such as carbon black rubber compound.

A conventional footwear midsole is a unitary, polymer foam structurethat extends throughout the length of the foot and may have a stiffnessor inflexibility that inhibits the natural motion of the foot. Incontrast with the conventional footwear midsole, midsole 32 has anarticulated structure that imparts relatively high flexibility andarticulation. The flexible structure of midsole 32 (in combination withthe structure of upper 20) is configured to complement the naturalmotion of the foot during running or other activities, and may impart afeeling or sensation of barefoot running In contrast with barefootrunning, however, midsole 32 attenuates ground reaction forces andabsorbs energy to cushion the foot and decrease the overall stress uponthe foot.

Midsole 32 includes a connecting portion 40 and a siped portion 50.Connecting portion 40 forms an upper surface 41 and an opposite lowersurface 42. Upper surface 41 is positioned adjacent to upper 20 and maybe secured directly to upper 20, thereby providing support for the foot.Upper surface 41 may, therefore, be contoured to conform to the natural,anatomical shape of the foot. Accordingly, the area of upper surface 41that is positioned in heel region 13 may have a greater elevation thanthe area of upper surface 41 in forefoot region 11. In addition, uppersurface 41 may form an arch support area in midfoot region 12, andperipheral areas of upper surface 41 may be generally raised to providea depression for receiving and seating the foot. In further embodiments,upper surface 41 may have a non-contoured configuration.

The thickness of connecting portion 40, which is defined as thedimension that extends between upper surface 41 and lower surface 42,may vary along the longitudinal length of midsole 32. The thickness isdepicted graphically in FIG. 9A as thickness dimensions 43 a-43 c.Dimension 43 a, defined in forefoot region 11, may be approximately 3millimeters and may range from 1 to 5 millimeters, for example.Dimension 43 b, defined in midfoot region 12, may be approximately 8millimeters and may range from 1 to 11 millimeters, for example.Similarly, dimension 43 c, defined in heel region 13, may beapproximately 6 millimeters and may range from 1 to 10 millimeters, forexample. The thickness of connecting portion 40 may, therefore, increasein directions that extend from forefoot region 11 and heel region 13toward midfoot region 12. One skilled in the relevant art willrecognize, however, that a variety of thickness dimensions andvariations will be suitable for connecting portion 40.

Areas of connecting portion 40 that exhibit a relatively thin thicknesswill, in general, possess more flexibility than areas of connectingportion 40 that exhibit a greater thickness. Variations in the thicknessof connecting portion 40 may, therefore, be utilized to modify theflexibility of sole structure 30 in specific areas. For example,forefoot region 11 may be configured to have relatively high flexibilityby forming connecting portion 40 with a lesser thickness. A relativelylow flexibility may be imparted to midfoot region 12 by formingconnecting portion 40 with a greater thickness. Similarly, anintermediate flexibility may be imparted to heel region 13 by formingconnecting portion 40 with a thickness that is between the thicknessesof forefoot region 11 and midfoot region 12.

Siped portion 50 forms a plurality of individual, separate sole elements51 that are separated by a plurality of sipes 52 a-52 l. Sole elements51 are discrete portions of midsole 32 that extend downward fromconnecting portion 40. In addition, sole elements 51 are secured toconnecting portion 40 and may be formed integral with connecting portion40. The shape of each sole element 51 is determined by the positions ofthe various sipes 52 a-52 l. As depicted in FIG. 8, sipes 52 a and 52 bextend in a longitudinal direction along sole structure 30, and sipes 52c-52 l extend in a generally lateral direction. This positioning ofsipes 52 a-52 l forms a majority of sole elements 51 to exhibit agenerally square, rectangular, or trapezoidal shape. The rearmost soleelements 51 have a quarter-circular shape due to the curvature of solestructure 30 in heel region 13.

The thickness of siped portion 50, which is defined as the dimensionthat extends between lower surface 42 to a lower surface of midsole 32,may vary along the longitudinal length of midsole 32. The thickness isdepicted graphically in FIG. 9A as thickness dimensions 53 a and 53 c.Dimension 53 a, defined in forefoot region 11, may be approximately 7millimeters and may range from 3 to 12 millimeters, for example.Similarly, dimension 53 c, defined in heel region 13, may beapproximately 12 millimeters and may range from 8 to 20 millimeters, forexample. The thickness of siped portion 50 may, therefore, increase in adirection that extends from forefoot region 11 to heel region 13. Oneskilled in the relevant art will recognize, however, that a variety ofthickness dimensions and variations will be suitable for siped portion50.

The combination of dimension 43 a and 53 a forms the overall thicknessof midsole 32 in forefoot region 11. Similarly, the combination ofdimensions 43 c and 53 c forms the overall thickness of midsole 32 inheel region 13. Although the configuration of footwear 10 issubstantially similar for footwear that is intended for males andfemales, experimental analysis has determined that males generallyprefer a lesser overall thickness differential than females.Accordingly, footwear 10 that is designed for males may have an overallthickness in forefoot region 11 that is 10 millimeters and an overallthickness in heel region 13 that is 18 millimeters, thereby providing adifferential of 8 millimeters. Footwear 10 that is designed for females,however, may have an overall thickness in forefoot region 11 that isalso 10 millimeters and an overall thickness in heel region 13 that is22 millimeters, thereby providing a differential of 12 millimeters.Footwear 10 that is designed for females may, therefore, exhibit anoverall thickness differential between forefoot region 11 and heelregion 13 that is greater than the thickness differential for males. Thegreater thickness differential may be imparted to footwear 10 byincreasing the thickness of the sole elements 51 that are located inheel region 13, for example.

The shape of each sole element 51, as discussed above, is determined bythe positions of the various sipes 52 a-52 l, which are incisions orspaces that extend upward into midsole 32 and extend between soleelements 51. Sipes 52 a-52 l also increase the flexibility of solestructure 30 by forming an articulated configuration in midsole 32.Whereas the conventional footwear midsole is a unitary element ofpolymer foam, sipes 52 a-52 l form flexion lines in sole structure 30and, therefore, have an effect upon the directions of flex in midsole32. The manner in which sole structure 30 may flex or articulate as aresult of sipes 52 a-52 l is graphically depicted in FIG. 7.

Lateral flexibility of sole structure 30 (i.e., flexibility in adirection that extends between a lateral side and a medial side) isprovided by sipes 52 a and 52 b. Sipe 52 a extends longitudinallythrough all three of regions 11-13. Although sipe 52 a may have astraight or linear configuration, sipe 52 a is depicted as having agenerally curved or s-shaped configuration. In forefoot region 11 andmidfoot region 12, sipe 52 a is spaced inward from the lateral side ofsole structure 30, and sipe 52 a is centrally-located in heel region 13.Sipe 52 b, which is only located in forefoot region 11 and a portion ofmidfoot region 12, is centrally-located and extends in a direction thatis generally parallel to sipe 52 a. In general, the depth of sipes 52 aand 52 b increase as sipes 52 a and 52 b extend from forefoot region 11to heel region 13.

Longitudinal flexibility of sole structure 30 (i.e., flexibility in adirection that extends between regions 11 and 13) is provided by sipes52 c-52 l. Sipes 52 c-52 f are positioned in forefoot region 11, sipe 52g generally extends along the interface between forefoot region 11 andmidfoot region 12, sipes 52 h and 52 i are positioned in midfoot region12, sipe 52 j generally extends along the interface between midfootregion 12 and heel region 13, and sipes 52 k and 52 l are positioned inheel region 13. Referring to FIG. 8, sipes 52 i-52 l are generallyparallel and extend in a medial-lateral direction. Although sipes 52c-52 h also have a generally parallel configuration and extend in themedial-lateral direction, sipes 52 c-52 h are somewhat angled withrespect to sipes 52 i-52 l.

The positions and orientations of sipes 52 a-52 l are selected tocomplement the natural motion of the foot during the running cycle. Ingeneral, the motion of the foot during running proceeds as follows:Initially, the heel strikes the ground, followed by the ball of thefoot. As the heel leaves the ground, the foot rolls forward so that thetoes make contact, and finally the entire foot leaves the ground tobegin another cycle. During the time that the foot is in contact withthe ground, the foot typically rolls from the outside or lateral side tothe inside or medial side, a process called pronation. That is,normally, the outside of the heel strikes first and the toes on theinside of the foot leave the ground last. Sipes 52 c-52 l ensure thatthe foot remains in a neutral foot-strike position and complement theneutral forward roll of the foot as it is in contact with the ground.Sipes 52 a and 52 b provide lateral flexibility in order to permit thefoot to pronate naturally during the running cycle. Similarly, theangled configuration of sipes 52 c-52 h, as discussed above, providesadditional flexibility that further enhances the natural, motion of thefoot.

Sipe 52 e has a width that is greater than the other sipes 52 a-52 d and52 f-52 l in order to permit reverse flex in forefoot region 11. Ingeneral, sipes 52 a-52 l permit upward flexing of sole structure 30, asdepicted in FIG. 7. In order to provide further traction at the end ofthe running cycle (i.e., prior to when the toes leave the ground), anindividual may plantar-flex the toes or otherwise press the toes intothe ground. The wider aspect to sipe 52 e facilitates the plantarflexion, thereby encouraging the natural motion of the foot duringrunning That is, sipe 52 e forms a reverse flex groove in midsole 32.Experimental analysis has determined that males have a tendency toplantar-flex in the forefoot area to a lesser degree than females. Inorder to facilitate the greater tendency to plantar flex in females,footwear 10 that is designed for females may include a sipe 52 e with aneven greater width, or sipe 52 d may also have additional width.Accordingly, both of sipes 52 d and 52 e may have increased width infootwear 10 that is designed for females, as depicted in thecross-section of FIG. 10A.

Outsole 33 includes a plurality of outsole elements that are secured toa lower surface of selected sole elements 51, and an indentation isformed in the lower surface of the selected sole elements 51 to receivethe outsole elements. As depicted in the figures, outsole 33 is limitedto heel region 13. In some embodiments, however, each sole element 51may be associated with an outsole element, or outsole 33 may extendthroughout the lower surface of midsole 32.

A plurality of manufacturing methods are suitable for forming midsole32. For example, midsole 32 may be formed as a unitary element, withsipes 52 a-52 l being subsequently formed through an incision process.Midsole 32 may also be molded such that sipes 52 a-52 l are formedduring the molding process. Suitable molding methods for midsole 32include injection molding, pouring, or compression molding, for example.In each of the molding methods, a blown polymer resin is placed within amold 60 having the general shape and configuration of midsole 32, asdepicted in FIGS. 13A and 13B. Mold 60 includes thin blades 61 thatcorrespond with the positions of sipes 52 a-52 l. The polymer resin isplaced within mold 60 and around each of blades 61, as depicted in thecross-section of FIG. 13C. Upon setting, midsole 32 is removed from themold, as depicted in FIG. 13D, with sipes 52 a-52 l being formed duringthe molding process. The width of sipes 52 a-52 l may be controlledthrough modifications to the thickness of blades 61 within mold 60.Accordingly, the reverse flex properties of sipe 52 e, for example, maybe adjusted through the thickness of the blade 61 that forms sipe 52 e,and the degree to which the other sipes 52 a-52 d and 52 f-52 l flex inthe reverse direction may be controlled through the thickness ofcorresponding blades 61. A suitable width range for the blades 61 thatform sipes 52 a-52 d and 52 f-52 l is 0.2-0.3 millimeters, whichprovides a relatively small degree of reverse flex. Similarly, asuitable width range for the portion of mold 60 (e.g., one of blades 61)that forms sipe 52 e is 3-5 millimeters, for example, which provides agreater degree of reverse flex.

Upper 20 and sole structure 30 have a structure that cooperatively flex,stretch, or otherwise move to provide an individual with a sensation ofnatural, barefoot running That is, upper 20 and sole structure 30 areconfigured to complement the natural motion of the foot during runningor other activities. As discussed above, exterior layer 14 includes aplurality of incisions 27 a and 27 b that enhance the stretch propertiesof upper 20 in specific areas and in specific directions. Whereasincisions 27 a may be oriented to permit stretch in the girth of upper20, for example, incisions 27 b may facilitate movement of the halluxand plantar-flexion. Incisions 27 a and 27 b also provide a generallymore flexible structure to upper 20 that complements the flexibility ofsole structure 30. As discussed above, midsole 32 includes a pluralityof sipes 52 a-52 l that enhance the flex properties of sole structure30. The positions, orientations, and depths of sipes 52 a-52 l areselected to provide specific degrees of flexibility in selected areasand directions. That is, sipes 52 a-52 l may be utilized to provide theindividual with a sensation of natural, barefoot running In contrastwith barefoot running, however, sole structure 30 attenuates groundreaction forces and absorbs energy to cushion the foot and decrease theoverall stress upon the foot.

The conventional sole structure, as discussed above, may have arelatively stiff or inflexible construction that inhibits the naturalmotion of the foot. For example, the foot may attempt to flex during thestage of the running cycle when the heel leaves the ground. Thecombination of the inflexible midsole construction and a conventionalheel counter operates to resist flex in the foot. In contrast, footwear10 flexes with the foot, and may have a configuration that does notincorporate a conventional heel counter.

The overall flexibility of sole structure 30 may be enhanced through theconfiguration of insole 31. With reference to FIG. 11, a lower surfaceof insole 31 is depicted as having a plurality of flexion lines 34 a-34l that generally correspond with the positions and configuration ofsipes 52 a-52 l. More specifically, flexion line 34 a extendslongitudinally through substantially the entire length of insole 31 andgenerally corresponds with the position of sipe 52 a. Flexion line 34 bextends longitudinally through only a portion of the length of insole 31and generally corresponds with the position of sipe 52 b. Similarly,flexion lines 34 c-34 l extend laterally from a medial side to a lateralside of insole 31 and generally correspond with the positions of sipes52 c-52 l. This configuration provides additional flexibility to solestructure 30 and enhances the articulated configuration imparted bysipes 52 a-52 l. A similar configuration is depicted in FIG. 12, whereinan insole 31′ includes a plurality of flexion lines 34 a′-34 l′ and twocushioning pads 35 a′ and 35 b′ formed of a compressible polymer foam.

The above discussion details the structure and configuration of footwear10, as depicted in the figures. Various modifications may be made tofootwear 10 without departing from the intended scope of the presentinvention. For example, incisions 27 a and 27 b may be formed in eitherof layers 14 or 15, or in both of layers 14 and 15. Incisions 27 a and27 b may also be formed in different orientations or positions toprovide different stretch characteristics, or a conventional heelcounter may be incorporated into upper 20. With respect to solestructure 30, the thickness of connecting portion 40 or the overallthickness of midsole 32 may vary considerably. In addition, the depth,orientation, and positions of sipes 52 a-52 l may be modified.

The present invention is disclosed above and in the accompanyingdrawings with reference to a variety of embodiments. The purpose servedby the disclosure, however, is to provide an example of the variousfeatures and concepts related to the invention, not to limit the scopeof the invention. One skilled in the relevant art will recognize thatnumerous variations and modifications may be made to the embodimentsdescribed above without departing from the scope of the presentinvention, as defined by the appended claims.

1. A method of manufacturing articles of footwear having a femaleversion and a male version, the method comprising steps of: molding solestructures of the articles of footwear to each include a connectingportion and a plurality of discrete sole elements extending from theconnecting portion, the sole elements being separated by a plurality ofsipes that extend into the sole structures; structuring the solestructures to have a first thickness in a forefoot region and a secondthickness in a heel region; and forming the female version such that adifferential between the first thickness and the second thickness isgreater than a corresponding differential in the male version.
 2. Themethod recited in claim 1, wherein the step of molding includes formingat least one of the sipes to have a greater width than other sipes. 3.The method recited in claim 1, wherein the step of molding includesforming the female version to include at least two sipes with a greaterwidth than other sipes, and forming the male version to include only onesipe with a greater width than other sipes.
 4. The method recited inclaim 1, wherein the step of molding includes placing blades within amold to for forming the sipes.
 5. The method recited in claim 4, furtherincluding a step of selecting a molding process from a group consistingof injection molding, pouring, and compression molding.
 6. A solestructure for an article of footwear, comprising: a connecting portion;and a plurality of discrete sole elements, wherein the connectingportion extends longitudinally along the length of the sole structure,the discrete sole elements extend downward from the connecting portionand are separated by a plurality of sipes extending upward into the solestructure, the plurality of sipes include a first sipe and a second sipethat extend in a longitudinal direction with respect to the solestructure, and a forefoot region of the sole structure includes curvedand generally parallel portions of the first and second sipes.
 7. Thesole structure recited in claim 6, wherein the first sipe is positionedcloser to a lateral side of the sole structure than a medial side of thesole structure in the forefoot region, the first sipe extends through amidfoot region of the sole structure, the second sipe is positionedbetween the first sipe and the medial side, the plurality of sipesinclude a plurality of third sipes that extend from the lateral sidetoward the medial side, at least one of the third sipes intersecting thefirst and second sipes in the forefoot region.
 8. The sole structurerecited in claim 7, wherein a first portion of the third sipes arepositioned in the forefoot region and a second portion of the thirdsipes are positioned in a heel region of the sole structure, the firstportion of the third sipes being angled with respect to the secondportion of the third sipes.
 9. The sole structure recited in claim 7,wherein a width of at least one of the third sipes is greater than awidth of other ones of the third sipes.
 10. The sole structure recitedin claim 7, wherein the plurality of third sipes is at least ten sipes.11. The sole structure recited in claim 6, wherein the first sipeexhibits an s-shaped configuration.
 12. The sole structure recited inclaim 6, wherein a depth of the first sipe increases as the first sipeextends from the forefoot region toward a heel region of the solestructure.
 13. The sole structure recited in claim 6, wherein the secondsipe is positioned in at least the forefoot region, and the second sipeis approximately centered between a lateral side of the sole structureand a medial side of the sole structure.
 14. The sole structure recitedin claim 6, wherein the first sipe is approximately centered between alateral side of the sole structure and a medial side of the solestructure in a heel region of the sole structure.
 15. The sole structurerecited in claim 6, comprising an outsole element secured to the lowersurface of the sole structure.
 16. The sole structure recited in claim6, comprising a plurality of outsole elements secured to the lowersurface of the sole structure, each of the outsole elements secured to adiscrete sole element.
 17. The sole structure recited in claim 16,wherein at least two of the outsole elements of the plurality aresecured to discrete sole elements in a heel region of the solestructure.
 18. The sole structure recited in claim 6, wherein the sipesare substantially perpendicular to the lower surface of the solestructure.
 19. The sole structure recited in claim 6, further comprisingan upper secured to the sole structure.